def demo(obj):
    print("形参值",obj)
    obj +=obj
    print("形参值",obj)

    print("===========值传递==========")
    string = "这是第一个测试"
    print("调用函数前实参值:",string)
    demo(string)
    print("调用函数后实参值：",string)
    print("============引用传递=========")
    list1 =['1',[2]]